AutoCAD DXF File Description

Voxler imports and exports 2D and 3D DXF files.

File Description

AutoCAD DXF files are ASCII files (i.e., they can be edited with a text editor or word processor) or binary files (cannot be edited) containing records indicating graphical entities and their attributes. They provide a medium of exchange with AutoDesk's AutoCAD program. DXF files are commonly used for storage and exchange of CAD and vector information.

File Format

The format of DXF files is complex and a detailed discussion is beyond the scope of a help file. Many books describing the DXF file format are widely available.

Graphics

Graphical information may be stored in the AutoCAD Drawing Exchange Format (DXF). Many programs, including AutoDesk Inc.'s AutoCAD (Computer Aided Design) program can import DXF files, allowing one to display and/or further manipulate the images. MTEXT (multi-line text block) background color in DXF import filter is supported.

3DSOLID is a proprietary format, and 3DSOLID entities are not supported in Voxler. If the .DXF file contains 3DSOLID objects, the 3DSOLID objects will be omitted during the import process.

ASCII or Binary Format

DXF files can be stored in either ASCII or Binary format. ASCII DXF files are the most versatile, since they can be displayed, edited, printed and transported to non-IBM machines (such as mainframes, minicomputers or Macintosh). However, they are somewhat bigger and take longer to read back into another application.

Table and Entities Sections

DXF files have two important sections.

·      The Tables section contains definitions of the various line styles and other attributes.

·      The Entities section contains specific information about each graphical entity (line, polygon, etc.) including coordinates and references to the attributes in the defined in the Tables section. All exported graphical entities are assigned to a layer named GSLAYER.

Filled Graphics

The DXF file format doesn't allow graphical entities (such as rectangles, polygons, etc.) to be filled. Therefore, only the edges of objects are exported. Their interior is always transparent. DXF is a difficult format, mainly because it can contain so many different types of data. The format is controlled and defined by Autodesk for use in its CAD program AutoCAD. The most common form of DXF is 7-bit text, but there are also two related binary formats, one that also uses the DXF extension and another that uses the DXB extension.

Line Styles

Lines styles are exported with equivalent AutoCAD-compatible line types. The document's internal line styles are assigned the following AutoCAD line type names:

Custom line styles in the document are assigned AutoCAD line type names of the form GSCUSTOM0, GSCUSTOM1, GSCUSTOM2, etc.

Color Numbers

Indexed DXF color numbers are assigned to each entity. Color numbers (1,2,3,…,255) are indices into AutoCAD’s internal color table. By convention, the first 7 color numbers are guaranteed to have known colors assigned to them by AutoCAD. They are:

AutoCAD has a default association of colors to color numbers, but the AutoCAD user is free to change the colors associated with color numbers 8 through 255. When exporting to DXF format, the color number of the color from the default AutoCAD color table closest to the actual color of the object is assigned to the entity in the DXF file. Unless you use only the seven colors listed above, the color of objects inside AutoCAD may be different than those in the application document.

AutoCAD 2004 and later versions support true colors. When user chooses AutoCAD 2004 or later in the Export Options dialog, true colors are written to the export file.

File Name Extensions

.DXF

Import Method

Choose the File | Import command.

Import Options Dialog

Specify import options in the AutoCAD DXF Import Options dialog.

Import Restrictions/Limitations

The fill and text in a .DXF will not appear when loaded into Voxler. Varying line widths are imported into Voxler and scaled from 0 to 4 points where size (points) = width (inches) / 72. However line widths greater than or equal to 0.05555556 inches will be rendered in Voxler at the same width (i.e. 4 points).

3DSOLID is a proprietary format, and 3DSOLID entities are not supported in Voxler. If the .DXF file contains 3DSOLID objects, the 3DSOLID objects will be omitted during the import process.

Export Method

Select a module and click the File | Save Data command.

Export Options Dialog

Specify export options in the AutoCAD DXF Export Options dialog.

See Also

File Format Chart

AutoCAD DXF Import Options Dialog

DXF AutoCAD DXF Export Options Dialog

File | Import